Metabolic Pathways, Third Edition: Volume VII: Metabolism of Sulfur Compounds deals with various aspects of the metabolism and biosynthesis of sulfur compounds such as coenzyme A, biotin, thiamine, and lipoic acid. The biochemistry of glutathione and the sulfur cycle is also discussed, together with sulfate activation and transfer; oxidative metabolism of cysteine and cystine in animal tissues; and enzyme defects in sulfur amino acid metabolism in humans. This volume is comprised of 15 chapters and begins with a discussion on the pathways of biosynthesis and dissimilation of coenzyme A, as well as the metabolic fate of exogenous coenzyme A in animals. The reader is then introduced to the chemistry, biosynthesis, metabolism, biological role, and biodegradation of biotin; the biosynthesis and function of thiamine; and the biosynthesis, dissimilation, and metabolic role of lipoic acid. Other sulfur compounds considered in this text are glutathione, cysteine and cystine, riboflavin, thiosulfate sulfurtransferase, mercaptopyruvate sulfurtransferase, and methionine. The final chapter is devoted to human diseases associated with enzyme defects in sulfur amino acid metabolism. This book will be a useful resource for biologists and biochemists.

List of Contributors

Preface


Contents of Other Volumes


Volumes in Series


Chapter 1 Metabolism of Coenzyme A


I. Biosynthesis of Coenzyme A


II. Coenzyme A as the Precursor of the Prosthetic Group of Acyl Carrier Protein


III. Dissimilation of Coenzyme A


IV. Metabolic Fate of Exogenous Coenzyme A in Animals


V. Metabolic Functions of Coenzyme A


References


Chapter 2 Biotin


I. Introduction


II. Chemistry


III. Biological Role of Biotin


IV. Biotin Biosynthesis


V. Biotin Degradation


VI. Concluding Remarks


References


Chapter 3 Thiamine, Biosynthesis and Function


I. Introduction


II. Biosynthesis of Thiamine


III. The Role of Thiamine


References


Chapter 4 Lipoic Acid


I. Introduction


II. Isolation and Some Properties


III. Biosynthesis and Dissimilation


IV. Summary of Metabolic Role


References


Chapter 5 Biochemistry of Glutathione


I. Introduction


II. Natural Occurrence of Glutathione and Related Compounds


III. Determination of Glutathione


IV. Biosynthesis of Glutathione


V. Utilization of Glutathione and Related -Glutamyl Compounds by the -Glutamyltranspeptidase-Cyclotransferase-5-Oxoprolinase Pathway


VI. Interconversion of Glutathione and Glutathione Disulfide


VII. Function of Glutathione in Mercapturic Acid Formation


VIII. Function of Glutathione as a Coenzyme


IX. Functions of Glutathione in Certain Tissues and Cells


X. Other Studies on Glutathione


References


Chapter 6 Covalent Adducts of Cysteine and Riboflavin


I. Introduction


II. 8a-Cysteinylflavin Thioethers


III. 8a-Cysteinylflavin Thiohemiacetals


IV. Metabolic Synthesis and Degradation of Covalently Bound Flavins


References


Chapter 7 Biochemistry of the Sulfur Cycle


I. The Sulfur Cycle in Nature


II. Assimilatory Sulfate Reduction


III. Dissimilatory Sulfate Reduction


IV. Chemolithotrophic Oxidation of Reduced Sulfur Compounds


V. Photolithotrophic Oxidation of Reduced Sulfur Compounds


VI. Oxidation of Reduced Sulfur Compounds in Animals


References


Chapter 8 Sulfate Activation and Transfer


I. Introduction


II. Sulfate Activation


III. Sulfate Transfer: The Sulfotransferases


IV. Role of Sulfate Activation in Taurine Biosynthesis


V. Other Mechanisms of Sulfation


VI. Somatomedin (Sulfation Factor)


References


Chapter 9 Sulfohydrolases


I. General Introduction


II. Enzymes Hydrolyzing C-O-SO3- Linkages


III. Enzymes Hydrolyzing P-O-SO3- Linkages


IV. Enzymes Hydrolyzing N-O-SO3- Linkages


V. Enzymes Hydrolyzing N-SO3- Linkages


VI. General Comments


VII. Addendum


References


Chapter 10 Thiosulfate Sulfurtransferase and Mercaptopyruvate Sulfurtransferase


I. Introduction


II. Thiosulfate Sulfurtransferase


III. Mercaptopyruvate Sulfurtransferase


References


Chapter 11 Methionine Biosynthesis


I. Introduction


II. Enzymes and Control of Enzyme Activity in Reactions Unique to Methionine Biosynthesis


III. Regulation of Enzyme Synthesis and Overall Methionine Control of Its Biosynthesis and Related Branch Pathways


References


Chapter 12 Biosynthesis of Cysteine and Cystine


I. Introduction


II. Synthesis of Cysteine by the Cysteine Synthase System


III. The Cystathionine Pathway of Cysteine Biosynthesis


IV. Cystathionine ß-Synthase of Rat Liver


V. Cystathionine -Synthetase of Bacteria


VI. -Cystathionase of Rat Liver


VII. Oxidation of Cysteine to Cystine


References


Chapter 13 Utilization and Dissimilation of Methionine


I. Introduction


II. Role of Methionine in the Biosynthesis of Spermidine and Spermine


III. Dissimilation of Methionine


References


Chapter 14 Oxidative Metabolism of Cysteine and Cystine in Animal Tissues


I. Introduction


II. Cytoplasmic Oxygenation of Cysteine to Cysteinesulfinic Acid


III. Metabolic Fate of Cysteinesulfinic Acid


IV. Mitochondrial Oxidation of Cysteine to Sulfate


V. Catabolism of Cystine


VI. Metabolic Origin of Taurine


References


Chapter 15 Enzyme Defects in Sulfur Amino Acid Metabolism in Man


I. Introduction


II. Cystathionine Synthase Deficiency


III. Defects in Homocysteine Methylation


IV. Cystathioninuria


V. Sulfite Oxidase Deficiency


VI. Hypermethioninemia


VII. Conclusions


References


Subject Index